Lemon Button Fern (Button sword fern) care

Light

Bright but filtered. Lemon Button Fern burns within days in unfiltered south-facing summer sun, and stops growing within months in deep shade. Prefers bright, indirect light but tolerates medium and lower light better than most ferns. An east or north window is ideal. Keep it out of direct midday sun, which fades and scorches the small round leaflets. If you only have a south window, set the plant back 1.5 m or hang a sheer curtain — both knock the intensity down into the right range.

Watering

Watering lemon button fern: when the top 1-2 cm of soil is dry, often every 5-7 days. The number that matters isn't the day of the week — it's how dry the top 2-3 cm of the pot feels. A finger in the soil tells you more than a watering app. After every watering, tip the saucer. Keep the soil consistently moist but not soggy; it is slightly more drought-forgiving than Boston fern, recovering from brief dryness. Water thoroughly and let excess drain. Avoid letting it sit in water, which rots the fine roots.

Soil and pot

Lemon Button Fern grows best in loose, humus-rich, moisture-retentive potting mix. Use a peat-free mix of coir, fine bark and perlite that drains well yet stays damp. Suited to terrarium substrates too. A pot with drainage holes prevents the crown and rhizomes from sitting wet and rotting. A pot with a working drainage hole is non-negotiable for this species — even free-draining mix will turn soggy in a closed planter. If you love the look of a decorative pot without a hole, use it as a cachepot around an inner nursery pot you can lift out to water.

Humidity and temperature

Lemon Button Fern sits happiest at around 40-60% humidity and 16-24°C (60-75°F). More tolerant of average household humidity than Boston ferns, but happiest above 40%. In very dry rooms tips may brown; a pebble tray, grouped plants or a terrarium keeps it lush. It is a reliable choice for closed cases and bottle gardens. If you keep the room above 16 year-round and avoid placing the plant near a cold draught, a hot radiator, or an air-conditioning vent, you have already handled the two biggest indoor stressors.

Fertilising

Feed lemon button fern sparingly. Feed monthly in spring and summer with a balanced liquid houseplant feed at half strength; this small fern needs little and is sensitive to fertiliser salts. Reduce or pause in autumn and winter. Flush the pot occasionally with plain water to clear salt buildup. Skip fertiliser entirely on a stressed, recently-repotted, or actively wilting plant — fertiliser salts make damage worse, not better. Wait for a round of healthy new growth before resuming a feeding rhythm.

Common problems

Below are the issues we see most often on lemon button fern in the Growli community. Each is annotated with the most common cause so you know where to start.

• Browning leaflets and edges — Usually the soil dried out too far or very low humidity. Keep the mix evenly moist and lift ambient humidity; trim spent fronds at the base.
• Yellowing fronds — Overwatering or poor drainage. Let the top of the soil dry slightly, ensure the pot drains, and avoid leaving water in the saucer.
• Leggy, sparse fronds — Too little light. Move to brighter indirect light; though shade-tolerant, very low light thins growth and dulls colour.
• Scale and mealybugs — Look for sticky residue or white cottony spots along fronds. Wipe off, isolate the plant, and treat with insecticidal soap if it spreads.

Propagation

Propagate by division in spring: unpot and split the rhizome clump into sections, each with roots and fronds, then repot. It also spreads by runners that root readily, making it easy to share. Spores form on frond undersides but home spore-sowing is slow and rarely needed. Propagation is the cheapest, most satisfying way to expand a collection — and it doubles as insurance against losing a mature plant to an accident. Take a backup cutting once the parent is established and healthy.

Toxicity to pets

Lemon Button Fern is pet-safe. ASPCA-listed as non-toxic to cats and dogs. Nephrolepis cordifolia is a true sword fern in the same genus as the ASPCA non-toxic Boston fern and carries no toxic principle such as calcium oxalates. Eating a little may cause only minor stomach upset from fibre rather than poisoning. If you keep cats, dogs, or curious children in the house, weigh placement carefully — a high shelf or a hanging planter is enough for casual safety. For severe ingestion incidents, call your local vet and the ASPCA Animal Poison Control Center (in the US, 888-426-4435).

Pet-safety status is sourced from the ASPCA Toxic and Non-Toxic Plant List, which catalogues the most-asked-about plants for cats, dogs, and horses.

Lemon Button Fern deep-dive guides

Every aspect of lemon button fern care, each with its own calibrated guide:

• Lemon Button Fern watering schedule
• Lemon Button Fern light requirements
• Best soil mix for lemon button fern
• Lemon Button Fern fertilizing guide
• When to repot lemon button fern
• How to propagate lemon button fern
• Lemon Button Fern growth rate & size
• Lemon Button Fern cold hardiness
• Lemon Button Fern temperature & humidity
• Is lemon button fern toxic to cats & dogs?
• Is lemon button fern toxic to cats?
• Is lemon button fern toxic to dogs?

Featured in these plant shortlists

Lemon Button Fern qualifies for 9 curated Growli shortlists — each one filtered objectively from our structured plant-care library, so the selection is consistent and checkable:

• Best pet-safe houseplants — Houseplants the ASPCA lists as non-toxic to cats and dogs — every one verified against the ASPCA toxic and non-toxic plant list.
• Best plants for a north-facing window — Houseplants for a north-facing window: bright, even, indirect light and no scorching direct sun. Each pick verified against its documented light needs.
• Best drought-tolerant houseplants — Houseplants that prefer to dry out — forgiving of forgotten watering and ideal for travel or busy weeks.
• Best pet-safe low-maintenance plants — Non-toxic to cats and dogs and forgiving of forgotten watering — the easiest safe choices for a busy pet household.
• Best pet-safe plants for bright light — Non-toxic to cats and dogs and happy in a bright, sunny spot — safe plants for your best-lit windowsill.
• Best small & tabletop houseplants — Compact houseplants that stay under about 40 cm — desk, shelf and windowsill plants that never outgrow a small space.
• Best cat-safe plants — Houseplants the ASPCA lists as non-toxic to cats (and dogs) — safe greenery for a home with a curious cat.
• Best dog-safe plants — Houseplants the ASPCA lists as non-toxic to dogs (and cats) — safe greenery for a home with a curious dog.
• Best small pet-safe plants — Compact, tabletop houseplants that are also ASPCA non-toxic to cats and dogs — safe greenery for a desk or shelf.
• Browse all 29 plant shortlists — pet-safe, low-light, drought-tolerant and more

Related guides

Lemon Button Fern is also commonly called Button sword fern or Fishbone fern.

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